1. Technical Field
This invention relates to optical interconnection arrangements for coupling a plurality of optical sources or emitters with a plurality of optical receivers and is especially applicable to so-called "microchannel relays".
2. Background Art
Microchannel relays may be used for a variety of purposes, including free-space optical interconnects (e.g. for communication from one printed circuit board to another, optical backplanes, digital and analog optical computing systems and optical data storage); emitter array-to-fibre ribbon/array couplers, and fibre ribbon/array-to-receiver couplers; and fiber ribbon/array-to-fiber ribbon/array couplers.
A typical microchannel relay comprises a plurality of parallel channels, each comprising a source, a receiver and a pair of lenses or lenslets. One lens collimates light from the adjacent source and the other lens collects the collimated light from the first lens and refocusses it at the adjacent receiver.
In most applications, the parallel microchannel relay channels, perhaps one thousand or more, must be provided in a very small space. A problem encountered with such high-density free-space microchannel relay systems is that their performance is very sensitive to misalignment of the lenses relative to each other and/or to the sources or receivers. In order to ensure maximum optical efficiency, it is desirable for the lenses to be as large as possible and adjacent lenslets in each array to be contiguous. Consequently, even small translational or rotational misalignments can reduce throughput significantly and increase the level of optical crosstalk between neighbouring optical communication channels. Although this problem can be ameliorated by using precision optomechanics, a disadvantage of doing so is a significant increase in cost.